doi:  10.3878/j.issn.1006-9895.1812.18204
热带气旋“苏迪罗”(2015)海上活动时段降水物理过程模拟诊断研究——海表温度敏感性试验

A Diagnostic and Numerical Study on Surface Rainfall Process of Tropical Cyclone Soudelor (2015) over the Ocean: Sensitivity Experiments on Precipitation Response to Sea Surface Temperature Change
摘要点击 134  全文点击 96  投稿时间:2018-07-26  
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基金:  国家重点基础研究发展计划 973 41175056国家重点基础研究发展计划(973)项目2015CB452804,国家自然科学基金项目41175056
中文关键词:  降水物理过程  热带气旋  海表温度  三维降水诊断方程
英文关键词:  Rainfall process  Tropical cyclone  Sea surface temperature  Three-dimensional WRF-based precipitation equation
           
作者中文名作者英文名单位
王晓慧中国科学院大气物理研究所云降水物理与强风暴重点实验室,北京100029;中国科学院大学,北京100049;宁波市海曙区气象局,浙江宁波315012
崔晓鹏中国科学院大气物理研究所云降水物理与强风暴重点实验室,北京100029;南京信息工程大学气象灾害预报预警与评估协同创新中心,南京210044;中国科学院大学,北京100049
郝世峰浙江省气象台,杭州310017
姜嘉俊宁波市气象局,浙江宁波315012
引用:王晓慧,崔晓鹏,郝世峰,姜嘉俊.2019.热带气旋“苏迪罗”(2015)海上活动时段降水物理过程模拟诊断研究——海表温度敏感性试验[J].大气科学,43(5):1125-1142,doi:10.3878/j.issn.1006-9895.1812.18204.
Citation:.2019.A Diagnostic and Numerical Study on Surface Rainfall Process of Tropical Cyclone Soudelor (2015) over the Ocean: Sensitivity Experiments on Precipitation Response to Sea Surface Temperature Change[J].Chinese Journal of Atmospheric Sciences (in Chinese),43(5):1125-1142,doi:10.3878/j.issn.1006-9895.1812.18204.
中文摘要:
      利用WRF模式,在前期工作(王晓慧等,2018)模拟试验基础上,设计敏感性试验,借助三维降水诊断方程,分析揭示了海表温度(SST)变化对热带气旋(TC)“苏迪罗”(2015)海上活动时段降水物理过程的可能影响。对照试验(CTL试验:SST随时间变化)和敏感性试验(SNC试验:SST固定为初始值)的SST存在明显差异(CTL试验平均SST低于SNC试验)。对比分析表明:两试验模拟的海上时段TC路径差异不大,但SNC试验模拟的TC强度较CTL试验偏强;TC环流区域内,两试验垂直速度差值在对流层基本为正(SNC试验上升运动更强),随着SST差值不断增大,垂直运动差值也不断加大;SNC试验的降水强度(PS)大于CTL试验,但PS差值随SST差值增大并非线性变化,体现了PS变化的复杂性;SNC试验的QWVA(垂直积分的三维水汽通量辐合/辐散率)均基本大于CTL试验(后期差别更大),SST的不同可通过影响垂直运动,造成QWVA的差异,进而影响PS;分析时段内,两试验TC环流区域大气均持续变干(正值QWVL),且存在较明显海面蒸发(正值QWVE),其中,两试验之间的QWVL差异不明显,但SNC试验的QWVE总体上强于CTL试验(尤其是分析时段中后期);两试验间云相关过程变率差异的时间变化复杂,最大差异量级与QWVE相当;SST对水凝物发展和深对流活动有一定影响,伴随SST差异的逐渐增大,水凝物含量差异也逐渐增大,液相水凝物中,雨滴差异较大,而与液相水凝物相比,冰相水凝物差异更为突出,尤其是较大的冰相粒子(雪和霰);SNC试验中,零度层下更多的霰粒子和雨滴,在更强上升运动配合下,有助于云滴和雨滴碰并(Pracw)及霰粒子融化(Pgmlt)微物理过程的加强,进而造成更强降水。TC环流区域时间和空间平均的物理量对比分析揭示,两试验降水物理过程定性上基本相似,但定量上存在明显不同,SNC试验的PS与CTL试验相比,增幅达8.8%,这种差异主要源于降水宏、微观物理过程的差异,其中,不同SST环境下QWVE的差异最为显著。
Abstract:
      To investigate possible impact of sea surface temperature (SST) change on surface rainfall process of tropical cyclone(TC) Soudelor over the ocean, sensitivity experiments are conducted using the Weather Research Forecasting (WRF) model and a 3D WRF-based precipitation equation based on the previous study of Wang et al. (2018). SST in the control experiment (CTL experiment, SST changes with time) is much different to SST in the sensitivity experiment (SNC experiment, SST remains constant). The results show that the difference in the simulated TC track over the ocean is small in the two experiments, but the simulated TC intensity in the SNC experiment is stronger than that in the CTL experiment. For the TC circulation, differences in the vertical velocity between the two experiments are basically positive in the troposphere (the SNC experiment yields stronger updrafts than the CTL). As the difference in SST increases, the vertical motion difference also becomes larger. Precipitation rate (PS )in the SNC experiment is larger than that in the CTL experiment, but the difference in PS between the two experiments increases non-linearly with the SST difference, which reflects the complexity of PS variation. QWVA (the three-dimensional moisture flux convergence or divergence rate) in the SNC experiment is basically larger than that in the CTL experiment (especially in the later period of the TC life cycle). This is because SST difference can affect vertical motion and cause QWVA difference, which in turn affects PS. During the study period of the two experiments, the atmosphere inside the TC continuously becomes drier (positive QWVL), and evaporation from the sea surface (positive QWVE) is significant.. There is little difference in QWVL between the two experiments. However, QWVE in the SNC experiment is generally stronger than that in the CTL experiment (especially in the middle and later stages of the TC life cycle). Temporal variations of the change rate of hydrometeor-related processes in the two experiments are complicated, but the magnitude of the maximum difference is comparable to that of QWVE. SST affects the growth of cloud hydrometeors content and deep convection, and thus differences in the variation of hydrometeors content gradually increased with SST difference between the two experiments. Among liquid-phase hydrometeors, large difference is found in raindrops, while differences in ice-phase hydrometeors, particularly large ice particles (snow and graupel), are even greater. In the SNC experiment, more graupel particles and raindrops are concentrated below the melting layer, which, concomitant with stronger updrafts, contribute to the occurrence and enhancement of Pracw(accretion of cloud water by rain) and Pgmlt(melting of graupels) and eventually enhance precipitation. Comparative analysis of regionally and temporally averaged macroscopic and microphysical processes related to the TC rainfall between the CTL and SNC experiments shows that the rainfall processes in the two experiments are qualitatively similar but quantitatively different. Compared with the CTL experiment, PS in the SNC experiment increased by 8.8%, which is mainly resulted from the difference in macroscopic and microscopic physical processes of precipitation between the two experiments. The different in QWVE isthe most obvious with different SST.
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